|
 The
superb range of quality polarimeter sample tubes manufactured
by Optical Activity can be used in almost all polarimeter
applications - and so, if you need to measure the tiniest
amount of an expensive essential oil, or if you have liters
of sample - one of our tubes is sure to be suitable. Our range
is extensive and has been continually added to for over 20
years, but if you still do not see the tube you need, we will
design and make a special tube - just let us know what you
want.
Our tubes
and cells use the internationally standard 30mm diameter collars.
Tubes are to class A standard as specified by
I.C.U.M.S.A.
where the tube material is stainless steel. This is in all
cases, Type EN 58 (316) quality stainless steel. End windows
are made from highly annealed strain free Crown glass held
in position by Nitrile O-rings (Viton O-rings are available
to special order for use with solvents such as chloroform
which attack Nitrile). The seal is glass to metal or glass
to glass, essential for accurate tube length determination.
The O-rings simply relieve pressure on the end windows, preventing
strain, and do not come into contact with the sample in ordinary
use.
To obtain
the best results from your polarimeter, it is important to
select the most appropriate tube for the particular sample
to be measured. If your polarimeter will accept a wide variety
of types and sizes of tubes, it makes the instrument more
versatile. All Optical Activity polarimeters can be used with
tubes as long as 200mm or as short as 5mm, with various tube
bores (we offer from 8mm down to 1.5mm as standard), single
sample or flow tubes which may be temperature controlled or
not, as required. This choice may prove confusing at first,
so please contact us so we can assist you in choosing the
best tube for your own use.
Polarimeter
Sample Tubes Selection Guide:
Tube
Type for Polarimeters:
For
a comparatively small number of samples,
brought for measurement one at a time, a SINGLE SAMPLE tube
is ideal - generally less expensive than a flow type tube
- and often useful for measuring odd samples even if a flow
system is normally used.
With
a large number of samples, especially large batches
of similar samples, a FLOW TUBE, connected for rapid sampling,
will save time - samples can be poured one after another
into a funnel without removing the tube from the polarimeter.
This system works well with all samples except those that
are highly viscous.
Dissimilar
samples - such as those with different solvents - are
probably best measured in single sample tubes. A flow system
can be used, provided steps are taken to thoroughly clean
and dry the tube between samples.
Quantity
of sample available. If you have plenty of sample, with
a flowtube connected for rapid sampling, you can use one
sample to displace the previous one - this is the quickest
method; however, you will obviously need more sample than
simply to fill a clean, dry tube.
For
an autosampling system, or continuous monitoring of flowing
fluids, a flow type tube must be selected.
Path
Length for Polarimeters:
Optical
rotation is directly proportional to path length - the
longer the tube, the greater the overall accuracy - it is
therefore desirable to use the longest tube possible; however,
there are other considerations:
- Sample
Quantity- less fluid is needed to fill a shorter tube.
- Dark
Samples - a shorter tube will allow you to get sufficient
light through to make a measurement (transmission decreases
logarithmically with path length, optical rotation directly,
thus halving the path length will give much more light while
reducing the accuracy by only 50%).
- Flowing
Samples - a long path length may integrate the changes
you are looking for.
- Comparision
with other work - it may be convenient to select a particular
tube length to allow direct comparison (provided the accuracy
is adequate) with published figures. The 'standard' length
for specific rotation is 1dm (100mm); the sugar industry
use 200mm in the definition of the International Sugar Scale.
Tube
Bore for Polarimeters:
The main
considerations are sample quantity, darkness, and viscosity.
Smaller bore tubes obviously require less sample; however,
larger bore tubes are generally easier to fill and clean especially
as the viscosity of the sample increases.
If the
bore of the sample tube is smaller than the beam diameter
of your polarimeter, light will be lost by the beam obstruction.
In Optical Activity polarimeters, the beam diameter is 4mm.
Tubes with bores less than 4mm will partially obstruct the
beam, and while not affecting the accuracy of the instrument,
will reduce the optical density tolerance. Tubes with bores
of 2.5mm or 1.5mm cannot therefore be considered suitable
for dark, colored, or cloudy samples. A 4mm or 5mm bore
tube is a good compromise to minimize the amount of sample
while remaining easy to fill and will not obstruct the beam.
Temperature
Control for Polarimeters:
For the
most accurate work, we generally advise controlling the temperature
of the sample tube by use of a chiller thermocirculator for
which a jacketed tube is necessary; if the temperature coefficient
is known, an alternative is to measure the sample temperature
and apply the necessary correction, but consideration of the
overall accuracy required may indicate that it is not essential.
It will depend on the rate that the optical rotation of the
sample (at the concentration being measured) varies with temperature
- some samples are not very temperature dependent, others
vary rapidly with temperature.
Back
to Top
Polarimeter
Sample Tubes Description:
|
Series
A1 Standard Single Sample Tubes in Stainless Steel:
|
With
solid, machine-turned brass end caps, plated for
long life (the sample fluid comes into contact only
with stainless steel and glass). The A1 tubes have
two fillers; the sample is poured into one filler
from an ordinary laboratory beaker, the second filler
allows air to escape, minimizing formation of bubbles.
Any bubbles that do form can be removed easily by
gently tilting the tube (rubber stoppers are available
if required - part no. 05-24). |
|
Series
A2 Jacketed Flow Tubes and Small Bore Tubes:
|
For
flow or single sample applications. The tube inlets
and outlets are extremely close to the end windows
so that in flow applications there is no dead volume
where bubbles or sample can be trapped. This unique
design feature means that the small bore versions
are easy to fill - use a hypodermic syringe which
fits the luer taper in the filler tubes of the 4
and 2.5mm bore sizes. All A2 tubes are made of stainless
steel, with plated brass end caps and are robust
and indestructible in normal use. |
|
Series
A2 Unjacketed Small Bore Tubes:
|
Maximum
path length with minimum volume. If temperature
control is required, select from A2 jacketed series
which are identical except for the addition of the
thermostatable jacket. |
|
Series
A4 Small Volume Cells:
|
Stainless
steel with two fillers which have female luer tapers.
For single sampling, use a hypodermic syringe (with
standard luer taper end) to fill the cells; air
is forced out of the second filter, eliminating
all bubbles. A4 cells are also exceptionally suitable
for flow applications or for filling with an autosampler
as the cell design forces the sample fluid to flow
across the window ensuring complete purging with
no dead volume. Optionally we can supply A4 cells
with screw couplings for microbore tubing. |
|
Series
A4 Jacketed:
|
Small
volume cells. The 50 and 25mm path length stainless
steel A4 cells are available jacketed for sample
temperature control using fluid flow from a thermocirculator
(if temperature control is required for a 5 to 10mm
path length cell, a thermostatable "shoe" is available
- part no. 04-27). |
|
Series
A4-P Cells:
|
All
the features of the A4 series cells, but made from
glass-loaded PTFE, appropriate for acid samples. |
|
Series
F5 Jacketed Tubes:
|
Similar
to the A2 stainless steel jacketed flow tube but
with stainless steel funnel and siphon breaker fitted
for rapid sampling; simply use a piece of plastic
or similar tubing to run the siphon breaker outlet
to a collection/waste vessel and pour samples one
after another into the funnel. Each succeeding sample
will displace the previous one provided approximately
50ml of fluid is available (optimum sample volume
depends on tube size and type of sample). |
|
Series
F5 Unjacketed Tubes:
|
For
applications where sample temperature control is
not required. |
|
Series
P6 Pressure Tubes:
|
Suitable
for in-line flow use; will stand pressures up to
3 bar (not jacketed). All stainless steel construction.
Inlet/outlet tube outside diameter 6.35mm (¼ in.)
suitable for standard ¼ in. pressure fittings (such
as "Swagelok" (TM) or "Gyrolok" (TM) - not supplied
with the tube but available upon request). |
|
Series
G7 Glass Single Sample Tubes:
|
Similar
in design to the series A1 tubes with two filters,
offered for customers measuring acid samples which
would attack stainless steel. The glass tubes have
stainless steel collars and good quality machine-turned,
plated brass end caps. Samples are poured directly
into the 15mm diameter glass fillers from a beaker.
|
|
Back
to Top
Polarimeter
Sample Tubes Chart:
|
|
| Tube |
Part
No. |
|
Bore
(mm) |
Path
Length
(mm) |
Approx.
Volume
(ml) |
For
Flow Appli-
cations |
Accept
Luer
Taper |
| A1 |
8x200
stainless steel
8x100 s.s. |
04-01
04-02 |
*
*
|
8
8 |
200
100 |
10
5 |
No
No |
No
No |
| A2 |
8x200
jacketed s.s.
8x100
4x200
4x100
2.5x200
2.5x100 |
04-03
04-04
04-05
04-06
04-07
04-08 |
*
*
*
*
*
*
|
8
8
4
4
2.5
2.5 |
200
100
200
100
200
100 |
10
5
2.5
1.3
1.0
0.5 |
Yes
Yes
Yes
Yes
Yes
Yes |
No
No
Yes
Yes
Yes
Yes |
| A2 |
4x200
unjacketed s.s.
4x100
2.5x200
2.5x100 |
04-09
04-10
04-11
04-12 |
|
4
4
2.5
2.5 |
200
100
200
100 |
2.5
1.3
1.0
0.5 |
Yes
Yes
Yes
Yes |
Yes
Yes
Yes
Yes |
| A4 |
5x50
s.s.
5x25
5x10
5x5
2.5x25
2.5x10
2.5x5
1.5x10
1.5x5 |
04-15
04-16
04-17
04-18
04-19
04-20
04-21
04-22
04-23
|
*
*
*
*
*
*
*
|
5
5
5
5
2.5
2.5
2.5
1.5
1.5 |
50
25
10
5
25
10
5
10
5 |
1.0
0.5
0.2
0.1
0.125
0.05
0.025
0.02
0.01 |
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes |
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes |
| A4 |
5x50
jacketed s.s.
5x25
2.5x25 |
04-24
04-25
04-26 |
|
5
5
2.5 |
50
25
25 |
1.0
0.5
0.125 |
Yes
Yes
Yes |
Yes
Yes
Yes |
| A4-P |
5x50
PTFE
5x25 PTFE |
04-60
04-61 |
*
*
|
5
5 |
50
25 |
1.0
0.5 |
Yes
Yes |
Yes
Yes |
| F5 |
8x200
jacketed s.s.
8x100
|
04-30
04-31 |
*
*
|
8
8 |
200
100 |
10
5 |
Funnel
Funnel |
No
No |
| F5 |
8x200
unjacketed s.s.
8x100 |
04-32
04-33 |
|
8
8 |
200
100 |
10
5 |
Funnel
Funnel |
No
No |
| P6 |
8x200
s.s.
8x100 |
04-40
04-41 |
|
8
8 |
200
100 |
10
5 |
Yes
Yes |
No
No |
| G7 |
8x200
glass
8x100 glass |
04-50
04-51 |
*
*
|
8
8 |
200
100 |
10
5 |
No
No |
No
No |
* The
most popular sizes of tubes, usually available ex-stock, are
marked with an asterisk. Delivery of other types may take
a little longer.
OTHER
SIZES or SPECIAL DESIGNS can be made to order.
Please ask for a quotation.
Back
to Top
|
